Vulnerability · Published Mar 11, 2026 · Assigned by GitHub_M
CVE-2026-21888MQTT v5 Variable Byte Integer parsing out-of-bounds: get_var_integer()
High 7.5
In plain English
A high-severity out-of-bounds read in nanomq from nanomq. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 29% of all known vulnerabilities).
Severity (CVSS 3.1)7.5High
Exploit odds (30 days)0.4%top 71.1% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known
Official description
NanoMQ MQTT Broker (NanoMQ) is an all-around Edge Messaging Platform. MQTT v5 Variable Byte Integer parsing out-of-bounds: get_var_integer() accepts 5-byte varints without bounds checks; reliably triggers OOB read / crash when built with ASan. This affects 0.24.6 and earlier.
Affected products (as reported)
Weakness: CWE-125 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
References
- https://github.com/nanomq/nanomq/security/advisories/GHSA-cggc-6m7w-j7x5 x_refsource_CONFIRM
- https://github.com/nanomq/nanomq/issues/2192 x_refsource_MISC